Well known in the art are reinforced adhesive coated tapes including those called duct tapes which comprise a backing layer of polymeric material, a reinforcing scrim along a major surface of the backing layer, and a layer of adhesive along that major surface of the backing layer that covers the reinforcing scrim. The scrim provides reinforcing for the backing layer, and can be of non-woven fibers, or can be a rectangular grid formed of spaced fibers or bundles of fibers extending longitudinally along the backing layer interwoven with spaced fibers or bundles of fibers extending transverse of the backing layer. Such a rectangular grid restricts manual tearing of the tape to tears in either the transverse or the longitudinal direction, which is useful so that a rectangular portion can be torn out of the tape. Typically the adhesive for such reinforced tapes is a visually apparent pressure sensitive adhesive and is applied in a heavy layer so that it will conform and adhere to substrates of many different materials having many different surface textures. Thus such reinforced tapes have found many more uses than sealing the joints in ventilating ducts. Such reinforced tapes are available with backing layers of many different colors so that, for example, a tape of a color at least similar to that of the substrate on which it is to be applied can be used to help retain an appearance for the taped substrate that is as pleasing as possible, or a tape of a contrasting color can be applied to make the tape stand out.
One variation of the reinforced tape structure described above has been provided by extruding or laminating the polymeric backing layer of the tape onto the reinforcing scrim, causing the backing layer to form around and envelope the fiber bundles in the scrim, and then applying a layer of pressure sensitive adhesive to one surface of the backing layer. The backings of such reinforced tapes typically have depressions along their outer surfaces opposite the layer of pressure sensitive adhesive corresponding to spaces between intersecting bundles of fibers in their reinforcing scrims, so that the outer surfaces of the tapes have less pleasing appearance than may be desired for some purposes.
Also well known are adhesive coated tapes of a type called box sealing tapes that typically have a polymeric backing layer and a layer of pressure sensitive adhesive along one major surface of that backing layer, but which do not include a reinforcing scrim of the type described above. Both the backing and adhesive of such tapes have been made quite visually transparent which helps to retain an appearance for a substrate to which the tapes are applied that is as pleasing as possible; however, many of their backing layers either do not provide the strength that is provided by backing layers with reinforcing scrims, or, if they have such strength, will stretch before they break and can not be accurately torn by hand. Special treatment of some such backing layers can be provides so that they can be torn by hand, but such tearing typically occurs in only one straight direction.
One type of box sealing tape called “filament tape” does include fiberglass reinforcing fibers or reinforcing ribs along its backing, however those reinforcing fibers or ribs in that tape are easily seen so that the backing of the “filament tape” is not very transparent and has little tendency to become visually transparent when applied to a substrate, and the “filament tape” is very difficult to tear by hand.